scholarly journals Experimental evidence of dispersal of invasive cyprinid eggs inside migratory waterfowl

2020 ◽  
Vol 117 (27) ◽  
pp. 15397-15399 ◽  
Author(s):  
Ádám Lovas-Kiss ◽  
Orsolya Vincze ◽  
Viktor Löki ◽  
Felícia Pallér-Kapusi ◽  
Béla Halasi-Kovács ◽  
...  
Keyword(s):  
Empirical Support ◽  
Freshwater Ecosystems ◽  
Dispersal Ability ◽  
Feeding Experiment ◽  
Fish Eggs ◽  
Migratory Waterfowl ◽  
Dispersal Mechanism ◽  
The World ◽  
Fresh Feces ◽  
Internal Transport

Fish have somehow colonized isolated water bodies all over the world without human assistance. It has long been speculated that these colonization events are assisted by waterbirds, transporting fish eggs attached to their feet and feathers, yet empirical support for this is lacking. Recently, it was suggested that endozoochory (i.e., internal transport within the gut) might play a more important role, but only highly resistant diapause eggs of killifish have been found to survive passage through waterbird guts. Here, we performed a controlled feeding experiment, where developing eggs of two cosmopolitan, invasive cyprinids (common carp, Prussian carp) were fed to captive mallards. Live embryos of both species were retrieved from fresh feces and survived beyond hatching. Our study identifies an overlooked dispersal mechanism in fish, providing evidence for bird-mediated dispersal ability of soft-membraned eggs undergoing active development. Only 0.2% of ingested eggs survived gut passage, yet, given the abundance, diet, and movements of ducks in nature, our results have major implications for biodiversity conservation and invasion dynamics in freshwater ecosystems.

Career Counselling Effectiveness and Contributing Factors

2020 ◽  
Author(s):  
Susan C. Whiston
Keyword(s):  
Career Choice ◽  
Significant Influence ◽  
Empirical Support ◽  
Effect Sizes ◽  
Career Counselling ◽  
Contributing Factors ◽  
Considerable Evidence ◽  
Effective Strategies ◽  
The World ◽  
Meta Analyses

This chapter explores the research related to whether career counselling is effective for individuals with vocational issues. In particular, there is considerable empirical support for career counselling related to career choice issues and searching for employment. Hence, practitioners can use this evidence to convince administrators, policymakers, parents, students, and other constituencies of the worth of career counselling. In addition, the chapter provides empirical evidence that practitioners can use to improve their effectiveness in working with people with career issues. This discussion mainly focuses on the results from older and newer meta-analyses regarding the ingredients that have a significant influence on effect sizes or the critical ingredients in career counselling. For example, there is considerable evidence that support from individuals, including the counsellor, may play an important role in the effectiveness of career counselling. Other factors that contribute to effective practice are also identified and discussed. The chapter further explores the need for additional research that addresses the most effective methods for providing career counselling. As the world of work becomes increasingly complex, it is important that researchers continue to explore the most effective strategies for assisting people in finding satisfying, meaningful, and productive work.

scholarly journals Cyanobacteria, cyanotoxins, and their histopathological effects on fish tissues in Fehérvárcsurgó reservoir, Hungary

2021 ◽  
Vol 193 (9) ◽  
Author(s):  
Damjana Drobac Backović ◽  
Nada Tokodi ◽  
Zoran Marinović ◽  
Jelena Lujić ◽  
Tamara Dulić ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Fish Tissue ◽  
Freshwater Ecosystems ◽  
Abramis Brama ◽  
Histopathological Changes ◽  
Fish Tissues ◽  
The World ◽  
Encoding Gene ◽  
Microcystis Wesenbergii ◽  
Histopathological Effects

AbstractCyanobacteria are important members of lake plankton, but they have the ability to form blooms and produce cyanotoxins and thus cause a number of adverse effects. Freshwater ecosystems around the world have been investigated for the distribution of cyanobacteria and their toxins and the effects they have on the ecosystems. Similar research was performed on the Fehérvárcsurgó reservoir in Hungary during 2018. Cyanobacteria were present and blooming, and the highest abundance was recorded in July (2,822,000 cells/mL). The species present were Aphanizomenon flos-aquae, Microcystis flos-aquae, Microcystis wesenbergii, Cuspidothrix issatschenkoi, Dolichospermum flos-aquae, and Snowella litoralis. In July and September, the microcystin encoding gene mcyE and the saxitoxin encoding gene sxtG were amplified in the biomass samples. While a low concentration of microcystin-RR was found in one water sample from July, analyses of Abramis brama and Carassius gibelio caught from the reservoir did not show the presence of the investigated microcystins in the fish tissue. However, several histopathological changes, predominantly in gills and kidneys, were observed in the fish, and the damage was more severe during May and especially July, which coincides with the increase in cyanobacterial biomass during the summer months. Cyanobacteria may thus have adverse effects in this ecosystem.

Spatial and seasonal variability of emergent aquatic insects and nearshore spiders in a subtropical estuary

2019 ◽  
Vol 70 (4) ◽  
pp. 541 ◽  
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan
Keyword(s):  
Aquatic Insects ◽  
High Salinity ◽  
Aquatic Insect ◽  
Freshwater Ecosystems ◽  
Dispersal Ability ◽  
Insect Community ◽  
Insect Communities ◽  
Low Salinity ◽  
Subtropical Estuary ◽  
Adult Aquatic Insects

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.

The Future of Water

2019 ◽  
pp. 227-232
Author(s):  
Edward B. Barbier
Keyword(s):  
Water Security ◽  
Freshwater Ecosystems ◽  
Freshwater Ecosystem ◽  
World Population ◽  
Policy Reforms ◽  
Global Management ◽  
Market Signals ◽  
The World ◽  
The Future ◽  
The One

This concluding chapter looks at the future of water. There are two possible paths for managing water. First, if the world continues with inadequate governance and institutions, incorrect market signals, and insufficient innovations to improve efficiency and manage competing demands, most chronic water and scarcity problems will continue to worsen. The world will see a future of declining water security, freshwater ecosystem degradation, and increasing disputes and conflicts over remaining water resources. The alternative path to managing water is the one offered by this book. If, in anticipation of the coming decades of increasing water scarcity, humankind is able to develop appropriate governance and institutions for water management, instigate market and policy reforms, and address global management issues, then improved innovation and investments in new water technologies and better protection of freshwater ecosystems should secure sufficient beneficial water use for a growing world population.

Global Wars, Public Debts, and the Long Cycle

1983 ◽  
Vol 35 (4) ◽  
pp. 489-516 ◽  
Author(s):  
Karen A. Rasler ◽  
William R. Thompson
Keyword(s):  
Economic Development ◽  
Great Britain ◽  
Longitudinal Analysis ◽  
Public Debt ◽  
Significant Proportion ◽  
Empirical Support ◽  
Long Cycle ◽  
Public Credit ◽  
The World

The explanation of the rise and fall of the world system's leading powers in terms of uneven economic development tends to overlook the role of the creation and management of public credit and national debts. Prior to 1815, the Netherlands and Great Britain owed a significant proportion of their respective victories over the larger and wealthier states of Spain and France to the development of competitive financial capabilities. Winning, however, leads to higher absolute debt burdens which, prior to 1945, encouraged postwar reductions in governmental expenditures. In this fashion, world leaders have contributed to the erosion of their preponderant capability positions before the emergence of international rivals. These ideas are elaborated within the context of George Modelski's long cycle of world leadership theory and through a brief review of war-related financial problems between 1500 and 1815 and the consequent development of national debts. The longitudinal analysis of British and American public debt data provides collaborating empirical support.

First record of Stenostomum sphagnetorum (Platyhelminthes, Catenulida) from India

Zootaxa ◽  
2020 ◽  
Vol 4816 (3) ◽  
pp. 392-396
Author(s):  
DAIZY BHARTI ◽  
FRANCISCO BRUSA ◽  
SANTOSH KUMAR ◽  
KAILASH CHANDRA
Keyword(s):  
North America ◽  
South America ◽  
Marine Species ◽  
First Record ◽  
Freshwater Ecosystems ◽  
Ganga River ◽  
Knowledge Gap ◽  
Free Living ◽  
First Report ◽  
The World

Catenulida are mostly inhabitants of freshwater ecosystems, like ponds, streams, though the marine species are few (Larsson and Willems, 2010). About 110 species of catenulids are known worldwide, with most of the studies conducted in South America (Marcus, 1945a, 1945b; Noreña et al., 2005), North America (Kepner and Carter 1931; Nuttycombe and Waters, 1938) and Scandinavian Peninsula (Luther, 1960, Larsson and Willems, 2010; Larsson et al., 2008). The diversity of catenulids from India has not been studied intensively; however some reports on other turbellaria exists for the country (Annandale, 1912; Whitehouse, 1913; Kapadia, 1947; Basil and Fernando, 1975; Apte and Pitale, 2011; Kalita and Goswami, 2012; Venkataraman et al., 2015). The genus Stenostomum, however, has been studied extensively around the world with identification of over 60 species (Tyler et al., 2006-2016). This is first report of the genus from India. The present study was part of the project to catalogue the diversity of free living protozoan ciliates from the Hooghly stretch of the Ganga River during which the flatworms were found. The worms were studied based on the live observations, with recognition of characters which led to its identification. This study serves to fill knowledge gap in the freshwater flatworms from India. 

Review of global and China's policies on fish passages

Water Policy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 708-721 ◽  
Author(s):  
Ang Chen ◽  
Jingya Wen ◽  
Miao Wu ◽  
Pengyuan Wang
Keyword(s):  
Local Governments ◽  
Critical Issue ◽  
Fish Passage ◽  
Freshwater Ecosystems ◽  
Watershed Scale ◽  
Adverse Impacts ◽  
Foreign Countries ◽  
The World ◽  
Further Development ◽  
Operation And Management

Abstract Fish migrate up and down streams for reproduction in both sea and freshwater ecosystems over their life cycle. Over the last decades, fish passages have been provided to mitigate the adverse impacts induced by barriers. However, what is the proper type of fish passage and how to guarantee the effectiveness of operation are still under discussion. In this paper, global and China's policies on fish passages are reviewed. The development and main contents of relevant instruments are analyzed. The similarities and differences between China and foreign countries are compared, and issues in the fish protection and fish passages' management in China are identified. The results show that global policies on fish passages varied from local governments to continents. The design, operation, and management of fish passages are popular throughout the world. Duplication of authorities' responsibilities is the most critical issue in China. The paper recommends implementing a plan of environmental protection at watershed scale, and strengthening the monitoring of fish passages' operation and management. Further development directions of policies on fish passages' management have been proposed. The paper may help facilitate national policies on fish passages by integrating the effective measures of global experience.

scholarly journals A Review of Gregory Clark's A Farewell to Alms: A Brief Economic History of the World

2008 ◽  
Vol 46 (4) ◽  
pp. 946-973 ◽  
Author(s):  
Robert C Allen
Keyword(s):  
Economic Growth ◽  
Middle Class ◽  
Economic History ◽  
Industrial Revolution ◽  
Empirical Support ◽  
Living Standards ◽  
Preventive Check ◽  
The World ◽  
History Of

A Farewell to Alms advances striking claims about the economic history of the world. These include (1) the preindustrial world was in a Malthusian preventive check equilibrium, (2) living standards were unchanging and above subsistence for the last 100,000 years, (3) bad institutions were not the cause of economic backwardness, (4) successful economic growth was due to the spread of “middle class” values from the elite to the rest of society for “biological” reasons, (5) workers were the big gainers in the British Industrial Revolution, and (6) the absence of middle class values, for biological reasons, explains why most of the world is poor. The empirical support for these claims is examined, and all are questionable.

scholarly journals Martynia annua (tiger's claw).

2020 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
Seed Dispersal ◽  
Central America ◽  
New Caledonia ◽  
Medicinal Herb ◽  
Dispersal Mechanism ◽  
The World ◽  
The Caribbean

Abstract Martynia annua is grown as an ornamental and medicinal herb. Originally native to Mexico, Central America and the Caribbean, its effective seed dispersal mechanism has helped it spread throughout tropical and subtropical regions of the world as a weed of pastures, disturbed sites, roadsides, moist thickets, riverbanks and floodplains. Currently, it is listed as invasive in Australia, New Caledonia, China, India, Indonesia, Malaysia and Cuba.

scholarly journals Freshwater Crabs of Upper Baleh River, Sarawak

2018 ◽  
Vol 8 (1) ◽  
pp. 1-5
Author(s):  
Jongkar Grinang ◽  
Min Pui Yong ◽  
Adi Shabrani ◽  
Anita Muli ◽  
C. Lee Chien
Keyword(s):  
New Genus ◽  
Decapod Crustacean ◽  
Freshwater Ecosystems ◽  
Dispersal Ability ◽  
Formal Description ◽  
Aquatic Habitats ◽  
Forest Patches ◽  
Freshwater Crabs ◽  
Undisturbed Forest

Freshwater crabs are among the most threatened species, primarily due to their high levels of endemicity, poor dispersal ability, low fecundity and the relatively fragmented nature of freshwater ecosystems. Consequently, regional diversity of freshwater crabs can serve as surrogates for assessing the quality of aquatic habitats in the upper reaches of Baleh River in Sarawak. The six days of sampling during a scientific expedition in the area resulted in the collection of five species of freshwater crabs, including two notable discoveries. The freshwater crabs belong to the families Gecarcinucidae (Arachnothelphusa sp., Bakousa kenepai) and Potamidae (Ibanum aethes, Isolapotamon nimboni, one new genus). The formal description of the new genus and two new species will be made later in appropriate taxonomic journals. The new crab species tends to a specialist in habitat use, being found only from an unusual habitat - a sandy spring within undisturbed forests, near the Elite Honour Camp. These findings indicate that the undisturbed forest patches near the timber camp are important to support population of crabs.Keywords: Decapod crustacean, Gecarcinucidae, Potamidae, semi-terrestrial

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